If you are a Firefox (Mozilla) user:
set keyword.enabled to false in about:config
You can find an explanation here.

Mozilla Firefox 0.9 released! Get it here!

In computing the term localhost refers to the location of the currently used system. It is a loopback device which is assigned the IP address 127.0.0.1, which can be used by TCP/IP applications to talk to themselves if this is needed. (wikipedia)